title: The malignant phenotype of breast cancer cells is reduced by COX-2 silencing.
abstract: The cyclooxygenase (COX) pathway is currently targeted for therapeutic intervention in different cancers. We have previously shown that silencing of COX-2 in the poorly differentiated metastatic breast cell line MDA-MB-231 by RNA interference markedly delayed tumor onset and inhibited metastasis. To understand the functional effects of COX-2 silencing underlying the inhibition of tumor growth and metastasis previously reported, we investigated changes in these cells for a number of cancer-associated phenotypes. Cyclooxygenase-2-silenced cells were less able to acidify tissue culture medium, a response that could partly be attributed to decreased lactate production or export detected by reduced lactate in the medium. Consistent with the significantly reduced transcript levels of hyaluronan synthase 2, an enzyme responsible for the total level of hyaluronan secreted by these cells, COX-2 silencing resulted in lower hyaluronan levels secreted in culture medium. Inhibition of human umbilical vein endothelial cell network association in a coculture assay was also observed in COX-2-silenced cells. These data highlight the functional role of COX-2 in pathways that mediate increased malignancy.
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Stasinopoulos
authors.forename: Noriko
authors.initials: N
authors.lastname: Mori
authors.forename: Zaver M
authors.initials: ZM
authors.lastname: Bhujwalla
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018920:Coculture Techniques; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism*; D042783:Endothelial Cells / Q000502:physiology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006820:Hyaluronic Acid / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D019344:Lactic Acid; D006820:Hyaluronic Acid; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human